Magnetoresistive layer systems or sensor elements are known from the related art, whose operating point, for example, for use in motor vehicles, is shifted by auxiliary magnetic fields generated in various ways. In particular, the generation of such auxiliary magnetic fields by mounted macroscopic hard magnets or by field coils having current flowing through them is known. Besides that, German Patent Application No. DE 101 28 135.8 explains a concept in which a hard magnetic layer is deposited in the vicinity of a magnetoresistive layer stack, especially on or under the layer stack, which, above all, because of its stray field, couples into the actual sensitive layers. In this context, a coercivity that is as high as possible is foremost as target parameter and, on the other hand, the remanent magnetic field is foremost as limiting parameter. Furthermore, such a hard magnetic layer, in a vertical integration, effects an electrical short circuit of the adjacent sensitive layers of the magnetoresistive layer system, which limits a desired GMR effect or AMR effect, as well as the sensitivity of the layer system with respect to outer magnetic fields.
It is an object of the present invention to provide a possibility of cost-effectively and simply generating a magnetic bias field or auxiliary magnetic field which acts upon a magnetoresistive layer stack, so as thereby being able to produce magnetoresistive sensor elements, especially for use in motor vehicles, in an inexpensive and yet reliable manner.